Simple compressor wiring ?

[darkharts]

Hey guy's lots of good info,

Im finally out-fitting my garage and picked up a 220v 60g. compressor. I have an unused dryer receptacle on its own circut, and i was just going to pick up a plug at HD. I read the manual and as far as the connections to the switch i found no info.I have line, line, and a ground marked on the switch, the pluge will have red, black, white, and green.

From reading other posts, should it be red and black to the posts marked lines( no difference to which one per color) and then green to the grounding lug, with the white just taped off and unused?

Thanks in advance-

danny

 

[May Pop]

Correct 220 volt no neutral
Ron

 

[TNToy]

From reading other posts, should it be red and black to the posts marked lines( no difference to which one per color) and then green to the grounding lug, with the white just taped off and unused?

Yup. The red and black are your hot wires. Does not matter which is which.

Connect a ground to the third terminal, usually the center. The screw is almost always painted green on new plugs as well.

Neutral is un-needed unless the device will need 110v for some reason (like a timer circuit in an electronic device that operates on 110) - and those require a 4-prong plug and receptacle... so for a simple device like a compressor or most clothes dryers, you only have 3 wires.

Be careful in what style of plug you choose - most dryer type plugs are rated for 50A, and these have huge prongs on the male connector that are about 3/4" wide.

...But there are some small plugs/outlets that are good for 15A on 220v. Most upright 60 or 80 gallon compressors draw 15-18A, and are safe for a 20A breaker, but not for a plug that's only rated for 15.

 

[OctaneMotorsports]

Yup. The red and black are your hot wires. Does not matter which is which.

Connect a ground to the third terminal, usually the center. The screw is almost always painted green on new plugs as well.

Neutral is un-needed unless the device will need 110v for some reason (like a timer circuit in an electronic device that operates on 110) - and those require a 4-prong plug and receptacle... so for a simple device like a compressor or most clothes dryers, you only have 3 wires.

Be careful in what style of plug you choose - most dryer type plugs are rated for 50A, and these have huge prongs on the male connector that are about 3/4" wide.

...But there are some small plugs/outlets that are good for 15A on 220v. Most upright 60 or 80 gallon compressors draw 15-18A, and are safe for a 20A breaker, but not for a plug that's only rated for 15.

Now I know who to PM if I ever need help with electrical, lol.

 

[darkharts]

Thanks guys, iwill get the plug tommorow and some copper pipe and fittings and see what it does.

danny

 

[Roospike]

How many amps is the compressor motor ?

It was stated in this thread most 60-80 gallon compressors are 15-18 amp , that would be true for around a 3hp motor. 5 hp are around 25-28 amp , 7.5 are around 33 amp.

Keep your wire sized correct and the correct breaker for a compressor. I put a 80 amp breaker and a #6 wire on my 7.5hp compressor as the fire up draw is around 74 amps and 33 running amps, Electric motors are a different animal when it come to wiring and breakers.

 

[darkharts]

Re: Simple compressor wiring (oh-oh different plug) ?

It's only a 30 amp and the breaker is a 40. But my new thing is my plug is older then i assumed( my bad for not checking). I have a three pronged plug instead of a 4. so now i have black, green, and white.

So green is ground, black is hot, but what do i do with the white? The compressor has a ground and two line's marked- does the white become the second line?

The plug has two slots and one with an L shape blade at the top in a triangle pattern I got the right plug and the correct wire i just need to make sure the compressor conection is right. The wire cutter at home depot was vauge at best.

Thanks for any help in advanced,

danny

 

[Nosman]

Re: Simple compressor wiring (oh-oh different plug) ?

It's only a 30 amp and the breaker is a 40. But my new thing is my plug is older then i assumed( my bad for not checking). I have a three pronged plug instead of a 4. so now i have black, green, and white.

So green is ground, black is hot, but what do i do with the white? The compressor has a ground and two line's marked- does the white become the second line?

The plug has two slots and one with an L shape blade at the top in a triangle pattern I got the right plug and the correct wire i just need to make sure the compressor conection is right. The wire cutter at home depot was vauge at best.

Thanks for any help in advanced,

danny

White becomes your second "hot" but make sure you mark it as such with black tape so anybody servicing will know it.

 

[Roospike]

Re: Simple compressor wiring (oh-oh different plug) ?

It's only a 30 amp and the breaker is a 40. But my new thing is my plug is older then i assumed( my bad for not checking). I have a three pronged plug instead of a 4. so now i have black, green, and white.

So green is ground, black is hot, but what do i do with the white? The compressor has a ground and two line's marked- does the white become the second line?

The plug has two slots and one with an L shape blade at the top in a triangle pattern I got the right plug and the correct wire i just need to make sure the compressor conection is right. The wire cutter at home depot was vauge at best.

Thanks for any help in advanced,

danny

Your compressor motor is 30 amp ?

What horse power is it stated at?

What size wire are you running and how far is the compressor from the plug ?

 

[darkharts]

Re: Simple compressor wiring (oh-oh different plug) ?

Your compressor motor is 30 amp ?

What horse power is it stated at?

What size wire are you running and how far is the compressor from the plug ?

It's marked as 5 hp, but probably lower. I wired it and plumbed it last night and it ran fine for a minute. Today i tried it with the sysytem closed and it ran fine for a minute and now the motor switches back and forth on- off. I used some 8-3 wire that the HD guy said was more thenenough and its only about a 8 ft cord. The Compressor is right next to the outlet, and for my hobby use it will not likely be on full cylcle very often-

When it switches it is internal in the motor- the main switch doesn't seem to be trippin. The plug had no marking other then the white. Should i switch the line hookups- lets say its black then white to white then black?

Just don't know why the motor is having issues- could its reset be bad. Sorry for the silly questions, The unit was used but in good shape. The oil was changed often and is clean other then a dirty filter everything apperas fine. If the family gives me a break i will unhook the pipping and see if its load related.

thanks for ides, danny

 

[goodfellow]

Re: Simple compressor wiring (oh-oh different plug) ?

It's marked as 5 hp, but probably lower. I wired it and plumbed it last night and it ran fine for a minute. Today i tried it with the sysytem closed and it ran fine for a minute and now the motor switches back and forth on- off. I used some 8-3 wire that the HD guy said was more thenenough and its only about a 8 ft cord. The Compressor is right next to the outlet, and for my hobby use it will not likely be on full cylcle very often-

When it switches it is internal in the motor- the main switch doesn't seem to be trippin. The plug had no marking other then the white. Should i switch the line hookups- lets say its black then white to white then black?

Just don't know why the motor is having issues- could its reset be bad. Sorry for the silly questions, The unit was used but in good shape. The oil was changed often and is clean other then a dirty filter everything apperas fine. If the family gives me a break i will unhook the pipping and see if its load related.

thanks for ides, danny

Well -- I guess you start from the receptacle. Is it 4 (hot, hot, ground, neutral) or 3 wire (hot, hot, ground)? In each case take a volt meter and check to make sure you're getting the proper voltage across the hot leads and then from the hot leads to ground and/or neutral.

You should get ~240v across the two hot leads and ~120v from each of the individual hot leads with respect to ground and/or neutral.

If that checks out and you're properly wired at the compressor, then check out the breaker one more time. Breakers can go bad (without tripping). Your motor may be drawing more current than the breaker can handle -- it may not trip, but the resistance may be due to a bad breaker.

Can you try a different breaker?

Also, what brand of compressor/motor? There have been a slew of these complaints due to inferior Chinese manufactured motors.

 

[darkharts]

Re: Simple compressor wiring (oh-oh different plug) ?

You should get ~240v across the two hot leads and ~120v from each of the individual hot leads with respect to ground and/or neutral.

In a simple test from ground to white i get 120, from ground to black i get 240.

it's a 3 wire as i corrected it above.

It's an older ge motor on a devilbis(sp?) setup. im sure its just a rebranded model of a typical 5hp-60 gal vertical. It only gets hit when the system is closed and it goes under load. At about 20 psi it starts- with the motor cycling on and off. If i open the system it runs fine-(no load it runs fine). Sorry my electrical knowledge is limited- i hooked it up from nosman's post-

Would it be something as simple as switching the lines(blk &wht) at the switch? My manual for the compressor says zip abotu the hook up at the switch, and the two post are marked the same- line - line. The breaker is fine and the switch is fine- it's the motor that is switching on and off for a second or so.

Thanks for any pointers, danny

 

[wilbilt]

Re: Simple compressor wiring (oh-oh different plug) ?

In a simple test from ground to white i get 120, from ground to black i get 240.

That's not right. It sounds like either the receptacle or the cord is wired incorrectly.

3-wire dryer plugs are usually wired with two hots and a neutral, but no ground. Often there are 120V components in a dryer (timer, light, etc.), necessitating the neutral. The neutral is connected by a jumper inside the dryer to the dryer cabinet, letting it "act" as a ground, since the neutral will be bonded to the ground in the main panel. I never understood why the NEC allows this, as it doesn't in just about any other situation.

My dryer is located inside my manufactured (mobile) home, and code requires that it have a 4-wire cord (hot, hot, neutral, ground) and that the neutral-to-cabinet jumper be removed. Much safer this way.

From the measurements you obtained, it sounds like your "ground" is actually a "hot".

You should have 120V from either hot to ground (or neutral). The only way you will see 240V is if you measure across the two hots.

If you measure from the black to the white and get 120V, and not 240V, then the white is a neutral, and that "ground" is a hot.

 

[X-ray]

20a OCPD, 10awg thhn, 14/3 cord wire. At the picture with switch wires, the lower wires are going to the plug, the wires on top of screen go to compressor motor.

 

[Junkman]

Re: Simple compressor wiring (oh-oh different plug) ?

You should get ~240v across the two hot leads and ~120v from each of the individual hot leads with respect to ground and/or neutral.

In a simple test from ground to white i get 120, from ground to black i get 240.

it's a 3 wire as i corrected it above.

It's an older ge motor on a devilbis(sp?) setup. im sure its just a rebranded model of a typical 5hp-60 gal vertical. It only gets hit when the system is closed and it goes under load. At about 20 psi it starts- with the motor cycling on and off. If i open the system it runs fine-(no load it runs fine). Sorry my electrical knowledge is limited- i hooked it up from nosman's post-

Would it be something as simple as switching the lines(blk &wht) at the switch? My manual for the compressor says zip abotu the hook up at the switch, and the two post are marked the same- line - line. The breaker is fine and the switch is fine- it's the motor that is switching on and off for a second or so.

Thanks for any pointers, danny

This isn't the type of thing that you should be cutting your teeth on in the electrical education department. Very rarely will 120 volt do more than give you the shock that will knock you off your feet, but 220 volt can give you the shock that can end your life. If you don't know what you are doing ask a friend that is more experienced or hire an electrician to do it for you. It is better to spend $100 to get it done right, then to spend $5000 on a funeral. Just my opinion, and others might disagree, but I have see too often when a homeowner makes an electrical mistake that is fatal.

 

[darkharts]

Thanks all, Wilbilt got it right- I stayed away from the receptacle(self preservation-lol) and assumed green was ground. So now i learned two things and after switching the nuetral with green it flys and pressures up fast. I just hapend to have an older plug receptacle that didn't follow the normal layout.

Thanks for the help, once the sun comes up i will see how my new ingersol impacts work.

danny

 

[wilbilt]

Keep in mind that using the neutral as an equipment ground is not code "legal" (for some pretty good reasons).

Many have posted here that they are doing the same thing without any issues, so YMMV.

 

[goodfellow]

Keep in mind that using the neutral as an equipment ground is not code "legal" (for some pretty good reasons).

Many have posted here that they are doing the same thing without any issues, so YMMV.

Well said -- I'd go one step further and suggest that you have this circuit checked by a licensed electrician. Using neutral as a ground may suggests that a compromise was made somewhere in the initial installation.

 

[VDubJoe]

Dont assume anything with electricity or theres a good chance youll end up dead. By a good book or do some web searching. Its not hard once you get the knowlage.

Be safe.
Joe